macb: initial support for Cadence GEM

The Cadence GEM is based on the MACB Ethernet controller but has a few
small changes with regards to register and bitfield placement.  This
patch detects the presence of a GEM by reading the module ID register
and setting a flag appropriately.

This handles the new HW address, USRIO and hash register base register
locations in GEM.

v3: - convert to macb_is_gem() inline rather than storing a boolean
      flag
    - handle rx_overrun stats for gem

Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Tested-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/drivers/net/ethernet/Makefile b/drivers/net/ethernet/Makefile
index be5dde0..94b7f28 100644
--- a/drivers/net/ethernet/Makefile
+++ b/drivers/net/ethernet/Makefile
@@ -10,7 +10,7 @@
 obj-$(CONFIG_NET_VENDOR_AMD) += amd/
 obj-$(CONFIG_NET_VENDOR_APPLE) += apple/
 obj-$(CONFIG_NET_VENDOR_ATHEROS) += atheros/
-obj-$(CONFIG_NET_ATMEL) += cadence/
+obj-$(CONFIG_NET_CADENCE) += cadence/
 obj-$(CONFIG_NET_BFIN) += adi/
 obj-$(CONFIG_NET_VENDOR_BROADCOM) += broadcom/
 obj-$(CONFIG_NET_VENDOR_BROCADE) += brocade/